How to count the number of rows per group
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Blue
el 29 de Sept. de 2022
Respondida: David Hill
el 29 de Sept. de 2022
Hi, I simply want to count the number of rows per group (for unique combinations of a, b and c). Groups where either a, b, or c are NaN should have a number of rows of NaN in the desired_output table.
% Original table
a = [1, 1, 1, 1, 2, 3, 3, 3]';
b = [NaN, NaN, NaN, NaN, 10, 23, 23, 23]';
c = [NaN, NaN, NaN, NaN, 5, 6, 6, 6]';
T = table(a, b, c)
% desired_output
a = [1, 1, 1, 1, 2, 3, 3, 3]';
b = [NaN, NaN, NaN, NaN, 10, 23, 23, 23]';
c = [NaN, NaN, NaN, NaN, 5, 6, 6, 6]';
d = [NaN, NaN, NaN, NaN, 1, 3, 3, 3]';
desired_output = table(a, b, c, d)
Thank you,
4 comentarios
Image Analyst
el 29 de Sept. de 2022
I tried some ways using table2array and unique but none of them was a one-liner. If you have a few lines of code that does it, just go with that. Sometimes longer code is better because it's more readable and understandable rather than a cryptic one-liner that no one can understand.
Respuesta aceptada
David Hill
el 29 de Sept. de 2022
A=[a,b,c];
u=unique(A,'rows');
d=zeros(size(A,1),1);
idx=any(isnan(A),2);
d(idx)=nan;
f=find(~idx);
for k=1:length(f)
d(f(k))=sum(ismember(A,A(f(k),:),'rows'));
end
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